Fenway Community Health (FCH), a Boston community-health center, which has conducted HIV/AIDS research for more than two decades, proposes to establish a Clinical Trials Unit (based on its experience coordinating HIVNET and HPTN consortia), which has been invited to be affiliated with two HIV/AIDS Clinical Trial Leadership Groups: Prevention of HIV (HPTN) and Microbicides (MTN). FCH will oversee the Administrative Component of the CTU and will coordinate the activities of three Clinical Research Sites in southeastern New England including: FCH, Latin American Health Institute (LHI, Boston, MA) and The Miriam Hospital (TMH, Providence, Rl). The CTU proposes to enroll a racially and ethnically diverse cohort of participants in the following protocols: 1. to reduce HIV seroincidence in cocaine and stimulant users (N=250); 2. to assess the efficacy of novel antiretrovirals for pre-exposure prophylaxis to prevent HIV transmission (250); 3. to decrease HIV incidence in IDU with buprenorphine (150); 4. to assess and develop interventions for individuals acutely infected with HIV (100); 5. to enroll high risk women in microbicide preparedness studies (100); 6. to assess oral versus topical tenofovir (20); 6. to evaluate a novel microbicide (20); 7. to compare a new microbicide with a placebo gel in a Phase II study (40); 8. to enroll high risk women in a Phase III study (200); 9. to enroll recently infected trial participants into observational studies (over 90% of newly infected patients). All 3 CRSs have worked together in the HPTN, enrolling distinctive populations of at risk and HIV-infected people, with FCH focusing on MSM, LHI on Latinos, and TMH on women. The current proposal demonstrates the ability of each CRS to increase and diversify its ability to enroll relevant populations for these trials. Each CRS has the infrastructure necessary for the conduct of effective and ethical trials, including well-trained, GCP-compliant staff; clinical and laboratory resources, experience with data collection, transmittal, and analysis; IRBs with FWAs; independent community advisory boards. The leadership of the CTU and participating CRS has worked together on multiple USPHS -funded research protocols, and demonstrate in this proposal the mechanisms to optimize the complementary strengths of the collaborative investigators, including experience working with diverse populations, plans for maximal efficiency in resource utilization, and mentoring of new investigators. ADMINISTRATIVE COMPONENT: